public class ProjectAlpha{
    public static void main(String[] args){
        float distance_in_ab = 1000,fly_time;
        int hit_b=0;
        while(true){
            if(distance_in_ab>1){
                fly_time = distance_in_ab/60;
                hit_b+=1;
                distance_in_ab -= 20*fly_time;
            }
            else{
                break;
            }
            //System.out.printf("Debug:fly_time="+fly_time+" distance_in_ab="+distance_in_ab+" hit_b="+hit_b+"\n");
        }
        System.out.printf(hit_b-1);
    }
}